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[pattern] Fix acquiring outside of source bounds

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Restrict the area we acquire from the source image to the bounds of
the source image, even when we have an identity matrix. This handles
circumstances where the pattern extents may be enlarged due to
filtering, for example when applying a bilinear filter.

This patch replaces the open-coded rectangle intersection which has
already proven itself to be a source of bugs.

(Patch ported to master by Chris Wilson, all bugs are his.)
This commit is contained in:
Owen W. Taylor 2008-09-28 23:30:22 +01:00 • committed by Chris Wilson
parent 6d0f2c4421
commit 6ef4bd4ecf
1 changed files with 31 additions and 30 deletions
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61
src/cairo-pattern.c
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@ -1768,8 +1768,7 @@ _cairo_pattern_acquire_surface_for_surface (cairo_surface_pattern_t *pattern,
return status;
}
if (_cairo_surface_is_image (dst))
{
if (_cairo_surface_is_image (dst)) {
cairo_image_surface_t *image;
status = _cairo_surface_acquire_source_image (pattern->surface,
@ -1780,57 +1779,59 @@ _cairo_pattern_acquire_surface_for_surface (cairo_surface_pattern_t *pattern,
*out = &image->base;
attr->acquired = TRUE;
}
else
{
} else {
cairo_rectangle_int_t extents;
status = _cairo_surface_get_extents (pattern->surface, &extents);
if (status)
return status;
/* If we're repeating, we just play it safe and clone the entire surface. */
if (attr->extend == CAIRO_EXTEND_REPEAT) {
x = extents.x;
y = extents.y;
width = extents.width;
height = extents.height;
} else {
/* If we're repeating, we just play it safe and clone the
* entire surface - i.e. we use the existing extents.
*/
if (attr->extend != CAIRO_EXTEND_REPEAT) {
cairo_rectangle_int_t sampled_area;
/* Otherwise, we first transform the rectangle to the
* coordinate space of the source surface so that we can
* clone only that portion of the surface that will be
* read. */
if (! _cairo_matrix_is_identity (&attr->matrix)) {
* read.
*/
if (_cairo_matrix_is_identity (&attr->matrix)) {
sampled_area.x = x;
sampled_area.y = y;
sampled_area.width = width;
sampled_area.height = height;
} else {
double x1 = x;
double y1 = y;
double x2 = x + width;
double y2 = y + height;
cairo_bool_t is_tight;
_cairo_matrix_transform_bounding_box (&attr->matrix,
&x1, &y1, &x2, &y2,
&is_tight);
NULL);
/* The transform_bounding_box call may have resulted
* in a region larger than the surface, but we never
* want to clone more than the surface itself, (we
* know we're not repeating at this point due to the
* above.
*
* XXX: The one padding here is to account for filter
/* XXX: The one padding here is to account for filter
* radius. It's a workaround right now, until we get a
* proper fix. (see bug #10508)
*/
x = MAX (0, floor (x1) - 1);
y = MAX (0, floor (y1) - 1);
width = MAX (MIN (extents.width, ceil (x2) + 1) - x, 0);
height = MAX (MIN (extents.height, ceil (y2) + 1) - y, 0);
sampled_area.x = floor (x1) - 1;
sampled_area.y = floor (y1) - 1;
sampled_area.width = ceil (x2) + 1 - sampled_area.x;
sampled_area.height = ceil (y2) + 1 - sampled_area.y;
}
x += tx;
y += ty;
sampled_area.x += tx;
sampled_area.y += ty;
/* Never acquire a larger area than the source itself */
_cairo_rectangle_intersect (&extents, &sampled_area);
}
status = _cairo_surface_clone_similar (dst, pattern->surface,
x, y, width, height,
extents.x, extents.y,
extents.width, extents.height,
&x, &y, out);
if (status == CAIRO_STATUS_SUCCESS && (x != 0 || y != 0)) {
cairo_matrix_t m;